Rotating head skin stapler

ABSTRACT

A surgical stapler having a trigger attached to a ratcheting mechanism for preventing the refiring of the stapler trigger with a staple loaded within a forming mechanism. In addition, the mechanism contains driver buffering means to prevent the sharp reduction in opposing force driving formation of a staple. The staples are constantly maintained in proper orientation during transfer from a track to the forming site, and are self-centering on the former, and have an oversized crown so that cold-worked areas on each staple do not hinder forming.

This is a continuation of application Ser. No. 479,318, filed Feb. 13,1990, abandoned.

FIELD OF THE INVENTION

The invention relates generally to surgical staplers. More specifically,the invention relates to skin staplers used during surgery. Mostspecifically, the invention relates to surgical skin staplers havingrotating heads.

BACKGROUND OF THE INVENTION

In recent years, the use of skin staplers has become one of thepreferred methods of wound closure. Skin staplers rapidly and accuratelyclose surgical wounds. Effective tissue eversion during skin staplingallows for rapid healing, and reduces the possibility of infection.

Nonetheless, as skin staplers have improved, so has the need forincreased reliability and various new and unforeseen characteristics.Thus, it is greatly desirable to provide skin staplers which containreliable staple feeding mechanisms. Previous staple feeding mechanismshave either been bulky or complex, or even quite unreliable. In order toform a more accurate skin stapler, the need exists for a reliablefeeding mechanism able to fit within a staple cartridge or track, anddemonstrate a thin profile in order to provide accurate, yet visiblestaple placement onto a surgical site.

In addition, previous systems have contained unreliable drivemechanisms. Previous systems must proceed completely along a singlestroke to be fired. Not completely firing this type of stapler haspreviously increased the likelihood of jamming, causing delay andunreliability in the system. Of course, even if one disregards thepossibility of the stapler jamming, if no provision is made for stoppingthe firing sequence, it is possible to lose accurate control andplacement of the surgical staple.

In many staplers, feel of the mechanism is quite important. If thesurgeon is able to "feel" a staple as it is being driven into the skin,the surgeon can properly place the staples and close the wound.Extremely important to such "feel" is the completion of the drivingstroke. Inadvertently, the triggering mechanism goes through a rapidchange in the force encountered at the stapling site. This may cause thetrigger mechanism to "jump" in the surgeon's hand, due to recoil fromthese forces. This affects the feel to the surgeon, who desires a verysmooth stroke in the stapler.

In addition, the track in which the staples are formed has been verydifficult to control in manufacturing processes. This is due, in part,to the very tight manufacturing tolerances through which the staple andcartridge must be held to prevent malforming of the staple. In somestaplers, especially those where the preformed staple is larger in widththan its final formed shape, it is difficult to control the formation ofthe staple while allowing for accurate placement. Thus, it is desirableto provide a system where the staple itself enhances its own accurateplacement at the forming site and, ultimately, in closing the wound.

Finally, when forming the staple, what is most necessary is repeatablycreating a properly shaped staple. This allows the surgeon to positionand properly place the staple on the skin. This creates the properenvironment on the skin for quick and safe wound healing. Furthermore,these desirable features of a skin stapler should be incorporated into askin stapler with a rotating head. The rotating head concept allows theuser to place the staple at the wound site, and then to examine the sitebefore closure, without raising the stapler from the surface of theskin. In this way, the user is able to maintain contact throughoutclosure.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide a skin staplerwith a rotating head where the staples are reliably transferred from thecartridge track in which the staples are maintained to the stapleforming site.

It is another object of the invention to provide a stapler where theuser can relax the grip on the stapler driving mechanism withoutpotentially harming the formation of the staple, or jamming the staplesin the staple forming track.

It is yet another object of the invention to provide a smooth andaccurate placement and closure of the staple without "snap" felt in thetrigger mechanism.

It is still another object of the invention to allow ease of manufacturewhile ensuring accurate placement and positioning of staples on thestaple former and in the skin.

It is yet another object of the invention to center the staples on ananvil surface prior to and during staple forming to achieve aconsistently more precise formed skin staple.

It is finally an object of the invention to incorporate all of thesecharacteristics into a stapler containing a rotating staple head,whereby staple forming precision, reliable ease of function, andaccuracy are embodied in a stapler having many versatile wound closurecapabilities.

These and other objects of the invention are accomplished in a surgicalstapler with a rotating head where the staple transfer mechanismcontains a lifter spring which provides the force necessary to lift thestaple across the stapler head from a feeding track into a parallelstaple forming track. This lifter mechanism supports the staple crownand legs to properly maintain the staple in position before the formingstroke. The lifter mechanism also contains a tab which maintains thestaple position on the staple lifter until the staple is moved to thestaple forming track.

At the opposite end of the stapler, the driving mechanism contains aratcheting means which allows the user to relax the stroke duringforming, and yet prevent jamming. A buffer mechanism provides aresistive force to the driver mechanism, thus spreading staple formingforces and minimizing any "snap" during the final stages of stapleforming.

Finally, the stapler has a wing-shaped forming mechanism which closelyparallels the winged shape profile of the staples. This former mechanismcenters the staple on the anvil and ensures reliable and consistentstaple formation and placement on the skin. A reduced anvil size causesthe staple to maintain an accurate and precise shape during forming.

These objects of the invention will be better understood by thefollowing Detailed Description of the Drawings taken in conjunction withthe Detailed Description of the Invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the rotating head skin stapler of thisinvention;

FIG. 2 is an exploded perspective view showing the replaceable staplecartridge removed from the rotating head;

FIG. 3 is a partial perspective view showing the rotating head in onepossible orientation;

FIG. 4 is a partial perspective view of the rotating head in anotherpossible orientation;

FIG. 5 is a cross-sectional view taken along line 5--5 of FIG. 2;

FIG. 6 is a view similar to FIG. 5 after compressing the handle andtrigger;

FIG. 7 is a fragmentary view in cross-section of the trigger mechanismof the invention;

FIG. 8 is a fragmentary view of the buffer mechanism;

FIG. 9 is a plan view of the drive block and drive train rotatingmechanism;

FIG. 10 is a perspective view of the drive block and drive trainmechanism;

FIG. 11 is a partial top plan view of the rotating head skin stapler:

FIG. 12 is a partial bottom plan view of the rotating head skin stapler;

FIG. 13 is a cross-sectional view taken along line 13--13 of FIG. 11;

FIG. 14 is a partial perspective view showing a formed staple whichreleased from the distal end of the staple cartridge;

FIG. 15 is a partial top plan view of the distal portion of the staplecartridge with the top of the cartridge partially broken away forclarity;

FIG. 16 is a cross-sectional view taken along line 16--16 of FIG. 15;

FIG. 17 is a partial bottom plan view of the staple cartridge just afterforming the staple;

FIG. 18 is a cross-sectional view taken along line 18--18 of FIG. 17;and

FIG. 19 is an exploded perspective view of the staple cartridge of thisinvention.

DETAILED DESCRIPTION OF THE INVENTION

As seen in FIGS. 1 through 4, the rotating head skin stapler 10 containsa base 20 housing a drive mechanism which is activated by a trigger 40squeezed within handle 50. The drive mechanism contained in the base 20causes staples to be fired from cartridge 70. The rotating head 60allows orientation of the cartridge 70 in any angular direction inrelation to base 20 on the wound surface to be closed, as best seen inFIGS. 3 and 4.

Various aspects of the rotating head skin stapler 10 will now beexplained. Intrinsic to the rotating head skin stapler 10 is rotatinghead 60. This rotating head 60 is attached to the base 20 by means ofcollar 64 enmeshed within holding cylinder 21 as better seen in FIGS. 5and 6. Drive train 66 is rotatably connected at its proximal end todrive block 44 and at its distal end contacts former 76 within the planeof cartridge 70. Drive train 66 fits axially into collar 64 on rotatinghead 60. Drive train 66 is generally flat in shape, and constantlyenmeshed between cartridge 70 and rotating head 60, as will be explainedlater. Because drive train 66 and cartridge 70 are fitted into thecenter of rotating head 60, and rotate about drive block 44, duringrotation they maintain positional relationship with base 20, so that theorientation of cartridge 70 is optional to the user. For instance, asseen in FIG. 4, cartridge 70 has been rotated to expose head plate 69.

At its proximal end, drive train 66 is rotatably engaged with driveblock 44. This is accomplished by inserting notched perforations 67 atthe proximal end of drive train 66 around circular node 47 of driveblock 44, as better seen in FIGS. 9 and 10. Thus, the notchedperforations 67 are free to rotate about circular node 47 to allow drivetrain 66 to rotate about drive block 44, as seen in FIGS. 5 and 6. Inthis way, wherever rotating head 60 is oriented with drive train 66contained therein, drive train 66 remains attached to drive block 44,and transfers force through the rotating head 60 and cartridge 70combination.

For operation of the stapler, it is necessary for drive train 66 to haveforce imparted on it by drive link or drive block 44. As drive train 66is rotatably attached by notched perforations 67 onto the drive blockcircular node 47, only force exerted along the same axis as drive train66 will be imparted from drive block 44.

As better seen in the enlarged and various views of the interior of base20 in FIGS. 5, 6, 7, 8, 9 and 10, drive block 44 is maintained on travelaxis 46 through use of guide channels 48. When drive block 44 is movedlinearly along guide channels 48, the wings 49 on drive block 44 aremaintained about guide channels 48. Thus, drive block 44 is ensured oftravel along travel axis 46. Trigger 40 contacts drive block 44, andtherefore imparts force on drive block 44 along travel axis 46.

Trigger 40 rotates about pivot 41 within handle 50. As seen in FIG. 7,elongated trigger projections 43 contact rear surface 51 of drive block44. Rotation of the trigger 40 about pivot 41 necessarily causes theuser to impart forces on drive block 44 along travel axis 46. This, inturn, causes motion of drive block 44 along travel axis 46, andoperation of the stapling mechanism in cartridge 70.

Improvements to the rotating head skin stapler 10 are seen in thedriving mechanism employed in use of trigger 40. Drive block 44 hasattached to it the pawl 28, by means of tabs 22 folded over the pawl 28,as seen in FIGS. 9 and 10. When trigger 40 is cocked by rotation aboutpivot 41, drive block 44 causes pawl 28 to move linearly in unison withdrive block 44 along axis 46. The rear of drive pawl 28 encounterssurface 30a on engagement block 30 at surface 29a on engagement tab 29,as seen especially at FIGS. 5 and 7 in a position normal to travel axis46. Engagement tab surface 29a becomes enmeshed with engagement blocksurface 30a to prevent rearward linear motion of drive block 44 alongtravel axis 46 by holding pawl 28 on teeth 38.

Relying further on FIGS. 6, 7 and 10, upon further motion of the trigger40, the stopping surface 32 of drive pawl 28 contacts multi-tooth rack36 on edges 34 of teeth 38. Stopping surface 32 is normal to travel axis46 and continues to prevent motion of drive block 44 into base 20 inincremental steps throughout the remainder of the stroke of trigger 40.Such continuous maintenance of the position of drive block 44affirmatively prevents jamming of the stapler 10, by preventing driveblock 44 and consequently trigger 40 from retracting linearly alongtravel axis 46 or recocking during a single stroke of trigger 40. Thestapling mechanism in cartridge 70 will not reload, and therefore twostaples will not be processed simultaneously at the forming site.

Accordingly, during motion of drive pawl 28 along multi-tooth rack 36,each of the teeth 38 hold drive pawl 28 at stopping surfaces 32 on edges34 until full rotation of the trigger 40 is accomplished. Then, the pawl28 acts like a leaf spring and recoils so that the surface of pawl 28clears the surface of multi-tooth rack 36. This occurs because tab 29ais no longer constrained by block surface 30a, so that pawl 28 now movesupward out of engagement with rack 36. This allows drive spring pawl 28to return to its original position. Return spring 42 causes trigger 40to return drive block 44 along travel axis 46 after one full stroke oftrigger 40.

As further seen in the enlarged view of drive block 44 as in FIG. 10,there are contained on block 44 winged-shaped buffers 26. Thesewing-shaped buffers 26 provide resistive force encountered by the userduring the forward linear motion of drive block 44, near completion ofthe stroke of the trigger 40. Ordinarily, at the completion of a firingstroke, staples 100 have been formed, but the user continues to drivetrigger 40. In order to reduce any "snap" in the feel of the trigger 40,due to the continued force of former 76 against staple crown 106 of the(now formed) staple 100, it is necessary to minimize forward linearmotion of drive block 44 and spread the force over a larger surface areaby imparting a resistive force opposite the direction of motion of driveblock 44, and thus reduce the pressure exerted on drive block 44.

As seen in FIGS. 5, 6 and 8, block-shaped stops 24 are provided in base20 which engage the buffers 26 near the end of the stroke of trigger 40.These stops 24 contain stopping surfaces 37 which cause the buffers 26to elastically bend near the end of the stroke of trigger 40. In thisway, the force actually imparted by the trigger 40 reduced by spreadingforces over a larger surface area near the end of the stroke, and theuser experiences no "snap" caused by impact of former 76 on staple 100after complete staple forming.

In summary, the trigger anti-jamming mechanism and the drive link bufferof the invention accomplish the following steps: The multi-tooth rack 36provides engagement surfaces 34 on the teeth 38 which are normal to thetravel axis 46 and therefore provide a resistive force parallel to thetravel axis 46. The drive pawl 28, made of a resilient material toresist permanent deformation, engages the multi-tooth rack 36 in adirection normal to motion of drive block 44 to provide resistive forcesparallel to travel axis 46. The engagement tab surface 29a on springpawl 28 provides early engagement with block engagement surface 30a inorder to prevent misfiring of the stapling mechanism in cartridge 70 atan earlier position of trigger 40 stroke. The engagement of the pawl 28with the rack 36 allows the user to have a smoother feel of the surgicalstapling instrument throughout the stroke of trigger 40.

In addition, with the buffers 26 molded as an integral part of the driveblock 44, as the stroke of the former 76 approaches the final stage ofcontact between staple crown 106 and anvil forming surface 94 (as laterexplained), buffers 26 contact stopping surfaces 37. Because buffers 26are elastic, they begin to bend and resist any continuing force impartedby drive block 44. In this way, forward motion of the block 44 is slowedand greatly reduces the impact of former 76 against the staple crown106. This results in a more consistent force to form the staples, andavoids any snap felt by the user during trigger 40 stroke.

Other aspects of the invention are seen in the staple cartridge 70.Specifically, as seen in FIGS. 17 through 19 drive train 66 is connectedto former 76 in the cartridge 70 by sliding plate 65 into grippingreceiver 75a. Former 76 contacts the first of a group of staples 100 atthe head of staple stack 110. These staples 100 contain wings 102, legs104, and crown 106. Lifter 90 holds a staple 100 in place and maintainsstaple 100 in position due to forced imparted by spring 88 on lifter 90,as later explained. During formation of a staple 100, crown 106 contactsthe forming surface 94 of anvil 78 at a forming site removed from staplestack 110. This is better explained in U.S. Pat. No. 4,811,886, assignedto the common assignee as this invention, and incorporated herein byreference.

As seen in the views of the former 76 in FIGS. 15 and 19, former edges98 are angled like the gull wing shaped wings 102 and legs 104 of staple100. With the improved former edges 98, the legs 104 becomeself-centering within staple forming track 120, and force is kept on theinside edges of the staple legs 104 during forming. In so doing, thestaple 100 stays centered on former 76 until staple 100 is formed aroundanvil forming surface 94. Alignment between former 76 and anvil 78 thusbecomes the controlling alignment criterion, rather than relying ontolerances of staple 100. If the staple 100 is positioned slightly toone side of the anvil forming surface 94, the funneling effect of theformer edges 98 biases or "pulls" the staple 100 to the center withinshoulders 99, and controls it throughout forming of the staple 100. Thecontinuous force imparted on the inside of staple legs 104 during thefiring stroke decreases the possibility of malformation of the stapleduring forming, as seen in FIGS. 15 through 18.

In addition, as seen in FIGS. 15 and 17, anvil forming surface 94 onanvil 78 in the cartridge 70 is smaller in width than staple crown 106.In this way, crown 106 is shaped entirely around anvil forming surface94. Because the crown 106 is wider than anvil forming surface 94, thecold worked areas of the staple found at the unions of crown 106 andwings 102 are shaped in spaced-apart relationship to the forming surface94. Thus, the cold worked areas of the staple 100 are avoided duringforming about forming surface 94, reducing forces necessary to form astaple 100.

Another improvement is seen in the lifter mechanism in cartridge 70 ofthe stapler. Lifter 90 is controlled by lifter spring 88 on the lowerstaple housing 82 of staple cartridge 70. Lifter spring 88 causes lifter90 to move one staple 100 from the stack of staples 110 in staplefeeding track 82a of the lower staple housing 82 of the cartridge 70.The staples in stack 110 are moved along feeding track 82a by feedershoe 84, which is urged distally by feeder spring 86. Lifter spring 88causes lifter 90 to lift a staple 100 across profile 96 in intermediatestaple housing 74, which defines a vertical passage between parallelfeeding track 82a and forming track 120.

The profile 96 on intermediate staple housing 74 has a shapecorresponding to the staples 100 and maintains the staple 100 on lifter90 properly within tab 74a of intermediate housing 74. Lifter 90therefore prevents transfer and double loading of staples from the stackof staples in feeding track 82a onto the staple forming stack 120.

Retainer cap 72 holds together upper staple housing 80 and lower staplehousing 82 and maintains feeder spring 86 in cartridge 70 so that theforce urging staple stack 110 along feeder track 82a and into a stapleforming track 120 is uninterrupted. Staple kick-off spring 92 causes theformed staples 100 to be kicked off from the anvil forming surface 94when formed and placed in the skin and former 76 is retracted. Topstaple housing 80 of cartridge 70 comprises the upper surface of formingtrack 120.

The staple transfer mechanism found in lifter 90 lifts the staplebetween the parallel staple stack 110 in staple feeding track 82a andstaple forming track 120 incorporated in cartridge 70. The single staple100 is supported along its crown 106 and legs 104 by the lifter 90during lifting from the staple feeding track 82a to staple formingposition in staple forming track 120. Tab 75 located on the distal endof the intermediate staple guide 74 provides resistive force to themotion of staple lifter 90 and maintains the staple in contact withlifter 90 and profile 96 through motion between the staple feeding track82a and staple forming track 120. Ears 90a on lifter 90 protrudetransversely into channels 82b of lower staple housing 82 to guidemotion of lifter 90. This staple transfer mechanism allows for reliablestaple feeding in the staple cartridge 70 within a thin profile. Thisallows for improved visible staple placement onto the surgical site.

While the invention has been described in connection with a particularlypreferred embodiment, it will be understood that the following claimsand their equivalents are meant to describe the invention.

What is claimed is:
 1. A surgical stapler comprising:a drive mechanismcontaining a trigger pivotably connected to said base; a staplingmechanism connected to said drive mechanism such that said trigger iscapable of undergoing a firing stroke in order to cause said drivemechanism to actuate said stapling mechanism wherein said trigger movessaid stapling mechanism along a drive axis; ratchet means on said baseand said driver mechanism, said ratchet means in contact with saidtrigger such that said ratchet means maintains said trigger atincremental positions along said stroke; said drive mechanism furtherincluding a return spring capable of maintaining a force on said triggerin a direction opposite that of said firing stroke, said return springconnected at one end to said drive mechanism and at an opposite end tosaid base; wherein said ratchet means comprises a pawl in contact withsaid trigger and a rack containing teeth and attached to said base, suchthat during the firing portion of said trigger stroke, said pawlcontacts said rack with enough contact force to overcome said returnspring force on said trigger, in order to maintain said trigger alongits stroke and on said drive axis and wherein said pawl is connected toa lead spring, such that said leaf spring causes said pawl to disengagewith said rack at the end of the firing portion of said trigger stroke,causing said return spring to retract said trigger to its originalposition, with said pawl remaining out of contact with said rack untilsaid trigger is in its original position; and wherein said pawl isattached to said trigger at the position along said drive axis wheresaid trigger on said drive mechanism is connected to said staplingmechanism.
 2. The stapler of claim 1 wherein said rack contains aplurality of teeth and said pawl contains an engagement surface suchthat said engagement surface contacts said teeth and said teeth resistthe return spring force on said trigger.
 3. The stapler of claim 2wherein said pawl moves along an axis parallel to said drive axis ofsaid stapling mechanism activated by said trigger and said teeth resistsaid return spring force parallel to said pawl axis.
 4. The stapler ofclaim 3 wherein said pawl further comprises an engagement tab and saidbase further comprises a block such that said tab engages said block atthe beginning of said stroke and before said engagement surface engagessaid teeth.
 5. The stapler of claim 4 wherein said stapling mechanism isconnected to said trigger at the position along said drive axis wheresaid return spring is connected to said trigger.
 6. The stapler of claim5 wherein said base holds said stapling mechanism in place such thatsaid stapling mechanism is rotatable about said drive axis.
 7. Thestapler of claim 1 wherein said base holds said stapling mechanism inplace such that said stapling mechanism is rotatable about said driveaxis.
 8. A surgical stapler comprising:a drive mechanism containing atrigger pivotably connected to said base; a stapling mechanism connectedto said drive mechanism such that said trigger is capable of undergoinga firing stroke in order to cause said drive mechanism to actuate saidstapling mechanism wherein said trigger moves said stapling mechanismalong a drive axis; ratchet means on said base and said drive mechanism,said ratchet means in contact with said trigger such that said ratchetmeans maintains said trigger at incremental positions along said stroke;said drive mechanism further including a return spring capable ofmaintaining a force on said trigger in a direction opposite that of saidfiring stroke, said return spring connected at one end to said drivemechanism and at an opposite end to said base; wherein said ratchetmeans comprises a pawl in contact with said trigger and a rackcontaining teeth and attached to said base, such that during the firingportion of said trigger stroke, said pawl contacts said rack with enoughcontact force to overcome said return spring force on said trigger, inorder to maintain said trigger along its stroke and on said drive axisand wherein said pawl is connected to a leaf spring, such that said leafspring causes said pawl to disengage with said rack at the end of thefiring portion of said trigger stroke, causing said return spring toretract said trigger to its original position, with said pawl remainingout of contact with said rack until said trigger is in its originalposition; wherein said pawl is attached to said trigger at the positionalong said drive axis wherein said trigger on said drive mechanism isconnected to said stapling mechanism; and wherein said trigger activatessaid stapling mechanism at a drive block, said drive block furtherhousing said pawl.
 9. The stapler of claim 8 wherein said staplingmechanism rotates about said drive axis at said drive block.
 10. Asurgical stapler comprising:a drive mechanism containing a triggerpivotably connected to said base; a stapling mechanism connected to saiddrive mechanism such that said trigger is capable of undergoing a firingstroke in order to cause said drive mechanism to actuate said staplingmechanism wherein said trigger moves said stapling mechanism along adrive axis; ratchet means on said base and said drive mechanism, saidratchet means in contact with said trigger such that said ratchet meansmaintains said trigger at incremental positions along said stroke; saiddrive mechanism further including a return spring capable of maintaininga force on said trigger in a direction opposite that of said firingstroke, said return spring connected at one end to said drive mechanismand at an opposite end to said base; wherein said ratchet meanscomprises a pawl in contact with said trigger and a rack containingteeth and attached to said base, such that during the firing portion ofsaid trigger stroke, said pawl contacts said rack with enough contactforce to overcome said return spring force on said trigger, in order tomaintain said trigger along its stroke and on said drive axis andwherein said pawl is connected to a leaf spring, such that said leafspring causes said pawl to disengage with said rack at the end of thefiring portion of said trigger stroke, causing said return spring toretract said trigger to its original position, with said pawl remainingout of contact with said rack until said trigger is in its originalposition; and a plurality of surgical staples and a staple former whichshapes said surgical staples about an anvil, said staples having a pairof sharpened legs connected by a crown, said former having a rectangularinner profile and edges for contacting said staple legs, and said edgeshaving an angular profile such that when said crown contacts said anvilsaid angular profile contacts said staple legs; and wherein said pawl isattached to said trigger at the position along said drive axis wheresaid trigger on said drive mechanism is connected to said staplingmechanism.
 11. In the stapler of claim 10, said staple legs being aroundsaid crown along the said edges of said former and said anvil, saidedges contacting said legs before said inner profile begins to bend saidlegs.
 12. The stapler of claim 11 wherein when said staples are formed,said staple legs have about a 90° angle about said anvil such that saidstaple legs bend around said anvil before release from said anvil, withsaid legs placed around either of said anvil sides and within said innerprofile, and said crown contacting said anvil.
 13. The stapler of claim12 wherein said anvil is shorter than an unformed crown of one of saidstaples.
 14. The stapler of claim 10 wherein said staples are containedin a cartridge, said cartridge maintained in a rotating head and saidstapler further including opposing means located in said base, saidopposing means acting on said trigger at the end of said stroke suchthat said opposing means act on said trigger during formation of saidstaple.
 15. The stapler of claim 14, said opposing means furthercomprising buffer on a drive block, said drive block connected to saidtrigger; andwherein said base further comprises stop means whichencounter said buffer on said drive block.
 16. The stapler of claim 15wherein said buffer are resilient and encounter said stop means frombefore said staple is fully formed along the stroke of said triggeruntil the completion of said trigger stroke.